cowork-bot: reject non-object plan JSON

Fail clearly when Terraform, CloudFormation, or Pulumi input decodes to a non-object JSON value.

Author: Coding-Dev-Tools

src/deploydiff/cloudformation_parser.py

@@ -52,6 +52,9 @@ def parse_cloudformation_changeset(changeset_json: str | dict[str, Any]) -> Depl
     else:
         data = changeset_json
 
+    if not isinstance(data, dict):
+        raise ValueError("Change set input must be a JSON object")
+
     changes: list[ResourceChange] = []
     changes_list = data.get("Changes", data.get("changes", []))
 

src/deploydiff/pulumi_parser.py

@@ -50,6 +50,9 @@ def parse_pulumi_preview(preview_json: str | dict[str, Any]) -> DeployPlan:
     else:
         data = preview_json
 
+    if not isinstance(data, dict):
+        raise ValueError("Preview input must be a JSON object")
+
     changes: list[ResourceChange] = []
 
     # Pulumi preview JSON has a "steps" array

src/deploydiff/terraform_parser.py

@@ -44,6 +44,9 @@ def parse_terraform_plan(plan_json: str | dict[str, Any]) -> DeployPlan:
     else:
         data = plan_json
 
+    if not isinstance(data, dict):
+        raise ValueError("Plan input must be a JSON object")
+
     format_version = data.get("format_version", "")
     changes: list[ResourceChange] = []
 

tests/test_parse_errors.py

@@ -59,3 +59,16 @@ def test_cloudformation_valid_dict_still_works(self):
         data = {"Changes": []}
         plan = parse_cloudformation_changeset(data)
         assert len(plan.changes) == 0
+
+    @pytest.mark.parametrize(
+        ("parser", "payload"),
+        [
+            (parse_terraform_plan, []),
+            (parse_cloudformation_changeset, []),
+            (parse_pulumi_preview, []),
+        ],
+    )
+    def test_json_array_is_rejected_with_clear_error(self, parser, payload):
+        """A decoded JSON value must be an object before parser-specific access."""
+        with pytest.raises(ValueError, match="JSON object"):
+            parser(payload)